Object locator

ABSTRACT

There is disclosed an object locator system for obtaining information about the location of an individual, animal or moveable object, having a lightweight, attached object locator, that is present in a region served by a two-way paging system and a global positioning satellite system. The object locator may be selectively activated to conserve power or enabled to respond only when beyond a boundary.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of Ser. No. 09/678,345 filedOct. 3, 2000 now U.S. Pat. No. 6,421,001 issued Jul. 16, 2002 which is acontinuation of Ser. No. 09/362,788 filed Jul. 28, 1999 now U.S. Pat.No. 6,172,640 issued Jan. 9, 2001 which claims priority in U.S.Provisional Patent Application Serial No. 60/140,040, filed Jun. 18,1999, and entitled “OBJECT LOCATOR.”

TECHNICAL FIELD OF THE INVENTION

The present disclosure pertains generally to electronic personallocating devices for determining the location or position of a pet, anobject or a person, and more particularly, a device for determining thelocation or position of the object by utilizing the capabilities oftwo-way paging systems and global positioning satellite systems.

BACKGROUND OF THE INVENTION

Tracking the location of an individual or an object or even an animalsuch as a domesticated animal or a pet that can move in unknowndirections over a considerable range of territory has been a concern fora number of years. A number of systems have been proposed which employexisting wireless communication capabilities but which tend to becumbersome, bulky, expensive or all of the above. With the advent ofglobal positioning system (GPS) services, it has been possible toprovide relatively inexpensive location systems for determining thelocation of a moving object. These have typically been utilized ontrucks to provide location information for companies that have largefleets of trucks in use at any one particular time. The position of anindividual truck is determined by coincident reception of signals fromat least three GPS satellites by a satellite receiver, which positioncan then be stored or can be transmitted to a central receiving stationvia some sort of wireless link. Moreover, the wireless link can be atwo-way communication link wherein the positioning information is onlytransmitted in response to receiving a request. However, the globalpositioning system (GPS) has some disadvantages in that it is relativelyslow in acquiring the location data and it is strongly dependent uponthe target object being in an open area where it is in a line of sightposition relative to at least three GPS satellites. A furtherdisadvantage, particularly in a small, portable unit, is that the GPSreceiver that must be included in a locating device requires the use ofsubstantial electrical energy during the period in which the locationinformation is being acquired and developed from the GPS system.Further, a small portable object locator, in addition to minimizing theuse of electrical power while being subject to less than idealorientations to enable quick and efficient location by the GPS system,must also be very simple and easy to use.

SUMMARY OF THE INVENTION

The object locator described in the present disclosure and claimedherein comprises an apparatus and a method for locating or tracking anindividual, an object or an animal having attached thereto an objectlocator operable to communicate with a base station location via atwo-way paging system and further operable to acquire locationinformation downloaded from a GPS system. A query for locationinformation about the individual object or animal may be transmittedfrom the base station over the paging system to a paging receiverintegrated with the object locator. Following the query, a signalenabling a GPS receiver in the object locator to acquire the locationinformation for the position of the individual, object or animal fromthe GPS system is generated in the object locator. Thus enabled, the GPSreceiver and the object locator receive the location information fromthe GPS system and store it in a memory in the object locator. The GPSreceiver in the object locator may then be disabled to conserve power.The location information stored in the memory of the object locator, maythen be loaded into a paging transmitter, also integrated with theobject locator, and transmitted via the paging system to the basestation. Upon receipt by the base station, the location information forthe individual, the object or the animal may be output in some form thatis readable or useful to a person at the base station or to a person whohas access to the base station or to a person accessible to the basestation.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and theadvantages thereof, reference is now made to the following descriptiontaken in conjunction with the accompanying Drawings in which:

FIG. 1 illustrates a block diagram of an object locator system of thepresent disclosure.

FIG. 2 illustrates a pictorial example of an object locator according tothe present disclosure;

FIGS. 3a-3 c illustrate a pictorial drawing of an object locatorsupported by a collar according to the present disclosure;

FIG. 4 illustrates a block diagram of the object locator of the presentdisclosure;

FIG. 5 illustrates a flowchart of the operation of the object locatorgenerally;

FIG. 6 illustrates a flowchart of the operation of the object locatorsubject to an additional external control;

FIG. 7 illustrates a pictorial drawing of a range dependent enablementsystem used to provide external control for the object locator;

FIG. 8 illustrates a block diagram of a base station that may be usedwith the object locator of the present disclosure;

FIG. 9 illustrates a block diagram of an alternate embodiment of a basestation that may be used with the object locator of the presentdisclosure; and

FIG. 10 illustrates a flowchart of the operation of the object locatorsystem of the present disclosure in obtaining location data via two-waypaging.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, there is illustrated a system block diagram ofthe object locator of the present disclosure. In FIG. 1, the objectlocator system 10 includes a two-way paging system 12, a globalpositioning satellite system 50 and the object locator 42. The two-waypaging system 12 is a conventional paging system that is well known inthe art, for example, such as illustrated and described in U.S. Pat. No.5,423,056 issued Jun. 6, 1995 to Lindquist, et al. and entitled ADAPTIVECELLULAR PAGING SYSTEM, which patent is incorporated by reference hereinin its entirety. The two-way paging system 12 interacts with a basestation 18 over a transmit path 14 and a receive path 16. The basestation 18 may, include a telephone, pager, and the like or may have aninput 20 for receiving a dialed-in telephone number from telephone set24 along communications path 22 or from wireless telephone set 25 overcommunications path 31. In general, the input 20 is responsive to dualtone multi-frequency (DTMF) tones transmitted by telephone set 24. Basestation 18 further has an output 26 from which location data to bedisplayed travels along path 28 to display 30. Display 30 may beconfigured to display location information in any of several forms, forexample, text, figures, graphics, or numbers.

Continuing with FIG. 1, the object locator system 10 of the presentdisclosure includes an object locator 42. In one of its operationalmodes, as a two-way paging transceiver, object locator 42 includes aninput 40 coupled to an antenna 36 along cable 38 for receiving signalstransmitted by two-way paging system 12 along path 32 and fortransmitting paging signals to the two-way paging system 12 along path34. The object locator 42 also includes an input 44 for receiving from aglobal positioning satellite (GPS) system 50 location informationsignals along path 52 to be intercepted by antenna 48 and conducted tothe object locator 42 along path 46 to input 44. The global positioningsatellite system 50 is of a conventional design well known in the art,an example of which is described in U.S. Pat. No. 5,726,660 issued Mar.10, 1998 to Purdy, et al. and entitled PERSONAL DATA COLLECTION ANDRECORDING SYSTEM, which patent is hereby incorporated by referenceherein in its entirety. Alternatively, location information signals maybe received from the Glasnost satellite system by the use of a receivingsystem configured for such reception.

In operation, object locator 42 is intended to be carried or attached toan individual, an object or an animal to be located or tracked by theobject locator system of the present disclosure. A user enters thesystem from the base station 18 by dialing the telephone number addresscorresponding to the object locator 42, which functions as a pagingtransceiver, on telephone set 24. The DTMF signal then travels alongpath 22 to input 20 of base station 18 where it is converted to a pagingtransmit signal and transmitted from antenna 15 along transmit path 14to the two-way paging system 12. The two-way paging system 12 relays thepaging message via transmit path 32 to the antenna 36 coupled to theobject locator 42. As will be described in more detail hereinbelow, theobject locator 42 processes the request for location informationtransmitted by base station 18, obtains location information from theglobal positioning satellite 50 and transmits a response containing thelocation information from antenna 36 along path 34 to the two-way pagingsystem 12 which, in turn, relays the location information signal alongpath 16 to antenna 15 of the base station 18 for processing and display30. Alternatively, wireless paths 14 and 16 along with antenna 15 mayinstead each comprise a standard telephone connection to a centraloffice.

Referring now to FIG. 2, there is illustrated a pictorial drawing of anobject locator 42 as it may be typically configured with a two-waypaging antenna 36 and a GPS receive antenna 48. The two-way pagingantenna 36 is coupled to object locator 42 along cable 38 to an theobject locator 42. Similarly, the GPS receive antenna 48 coupled along acable 46 to an input 44 on the object locator 42. The two-way pagingantenna 36 shown in FIG. 2 is intended to represent the fact that thisantenna in the object locator 42 is typically of the type found withtwo-way paging equipment. Such an antenna is typically mounted internalto the pager unit itself and is thereby necessarily of very smalldimension. However, there may be applications of the object locator 42of the present disclosure which may be optimized by the use of anexternal antenna such as shown in FIG. 2. Thus, the illustration of thetwo-way paging antenna 36 in FIG. 2 is not intended to be limiting, butmerely illustrative. The GPS receive antenna 48 is conventionallyreferred to as a “patch antenna” because of its flat, thin, rectangularshaped design. Typically such a patch antenna is intended to be disposedon an upward, relatively level surface in order to expose it to receivethe relatively weak signals transmitted by the global positioningsatellite system from the satellites arrayed in the GPS system. Theillustration in FIG. 2 thus demonstrates that both of the antennae usedin the system may be positioned for optimal reception and transmissionand connected to the object locator 42 using the flexible cables 38 and46 respectively for the two-way paging antennae 36 and the GPS receiveantenna 48.

Referring now to FIGS. 3a, 3 b and 3 c, there is illustrated a pictorialdrawing of an object locator 42 mounted on the lower side of a collar45. Such a collar 45 is configured for supporting an object locator 42around the body or neck of an animal which is intended to be tracked orlocated by the object locator 10 of the present disclosure. It will beobserved that the GPS antenna 48 is attached to the collar diametricallyopposite the position of the object locator. This is intentional as willbe described hereinbelow. The object locator is coupled to the GPSantenna 48 through a cable 46 which connects to the input 44 of theobject locator 42. This arrangement is illustrated in FIG. 3a and may bemore clearly shown by looking at the cross section A-A′ illustrated inFIG. 3b. In Section A-A′, a side view of the object locator mounted on acollar is shown wherein collar 45 supports the object locator 42 at itslower point and supports the GPS antenna 48 at its diametricallyopposite upper point. As before, the GPS antenna 48 is coupled throughcable 46 to input 44 of the object locator 42. Similarly, a side viewidentified by cross section B-B′ in FIG. 3c shows the opposite side ofthe collar-mounted object locator 42 assembly. In Section B-B′ there isshown the collar 45 which supports the object locator 42 at its lowerend and the patch antenna or GPS antenna at its diametrically oppositeupper end. Also shown in the Section B-B′ is a representation of thetwo-way paging antenna 36 which is coupled to input 40 of the objectlocator 42. It will be appreciated that many configurations are possiblefor arranging or attaching the object locator and its antennae to thecollar 45, including consolidating the locator and antenna as a unitlocatably mounted on or in the collar. Alternatively, the locator andantenna may be distributively arranged on or in the collar. However, itwill also be appreciated that the greater mass of the object locator 42relative to the mass of the GPS antenna 48 and the fact that they aremounted on diametrically opposite sides of the collar 45 enables theobject locator 42 to always remain in the lowest possible position andthe GPS receiving antenna to always remain in the highest possibleposition to optimize the reception from the GPS system 50. Not shown inFIGS. 3a-3 c is the mechanism such as a clasp or buckle arrangementwhereby the collar 45 may be opened and closed to secure the collararound the neck or body of the animal to be tracked or located. Again,many configurations are possible and will be apparent to those skilledin the art.

Referring now to FIG. 4, there is illustrated a block diagram for theobject locator 42 of the object locator system 10 of the presentdisclosure. A paging receiver 60 is shown coupling a data output 62along path 64 to an input of controller 66. Controller 66 includes amemory 68 for the storage of location data and a battery 70 for poweringthe object locator 42. This battery 70 is, in the present disclosure, arechargeable battery. This battery 70 can be a NiCad battery or aLithium battery. A solar cell 71 is provided for charging the battery70. Controller 66 includes a control output 72 which is coupled alongpath 74 to a control input 76 of paging receiver 60. Paging receiver 60receives paging communications via antenna 36R which are coupled alongcable 38R to RF input 40R of paging receiver 60.

Continuing with FIG. 4, there is shown a GPS receiver 78 for whichprovision is made to couple location data at an output 80 along path 82to an input terminal 84 of controller 66. GPS receiver 78 furtherincludes an enable input which is coupled from controller 66 at output86 along path 88 to the enable input 90 of the GPS receiver 78. The GPSreceiver 78 receives GPS signals from the global positioning satellitesystem 50 at antenna 48 which signals are coupled along path 46 to RFinput 44 of the GPS receiver 78.

Further illustrated in FIG. 4 is a paging transmitter 92 which isconfigured to transmit the location data provided by controller 66 atoutput 98 along path 96 to the data input 94 of paging transmitter 92.Controller 66 also provides an enable output at output 100 along path102 to the enable input 104 of paging transmitter 92. The pagingtransmitter 92, when enabled, transmits data received at the data input94 and couples the signal to be transmitted from the output terminal 40Talong path 38T to the paging transmitter antenna 36T for radiation tothe two-way paging system 12. It will be appreciated that the pagingsystem components, while shown as separate functional elements in FIG.4, may in fact be integrated into a single two-way paging transceiverwhich share a common antenna represented by reference number 36. Theillustration shown in FIG. 4 is intended to provide clarity as to thesignal paths that operate during the communication relationship of theobject locator 42 with the two-way paging system 12. A number ofconfigurations for coupling the antenna to the paging transceiver arefeasible, are well known in the art and will not be described furtherherein.

Continuing with FIG. 4, there is shown a block labeled “signal detector”106 having an output 108 which is coupled along path 110 to an enableinput 112 of controller 66. The signal detector 106 represents any ofseveral optional devices which may enable the more precise control ofthe object locator 42 by limiting the operation of the object locator 42to certain external conditions outside the paging communications or theGPS reception areas by the object locator 42. In the illustrativeexample shown in FIG. 4, the signal detector 106 provides an outputwhenever a threshold is crossed by signal energy from an independentsource. Such threshold, for example, may represent a limiting pointbeyond which the object locator 42 is enabled to operate. Such athreshold may represent a distance within which a position of the objectlocator will probably provide no useful information since the objectlocator may be within line of sight to the base station, for example.Other thresholds may be expressed in terms of time or altitude or as anazimuth heading. Alternatively, the object locator 42 may be programmedfor operating an alarm when the object locator 42 moves outside aperimeter. Such perimeter may be programmed by physically positioningthe object locator 42 at extremes of an area and, while the GPS 78receiver is operating, storing in the object locator's memory 68 thecoordinates reported, thus establishing a boundary outside of which theobject locator 42 will automatically report a position. Additionally,the perimeter may be defined by at least one coordinate stored in theobject locator memory 68. The perimeter is then determined by selectingstored algorithms to define the limits of a circular or othergeometrical shape outside of which the object locator 42 willautomatically report a position.

Continuing with FIG. 4, it will be appreciated that each of the majorfunctional blocks shown in FIG. 4 may be implemented by means ofintegrated circuitry which may be configured to fit within a housing ofvery small dimensions. For example, a pocket pager that typicallyoccupies a volume of approximately three to five cubic inches may weighapproximately four to six ounces. The controller 66 may comprise asingle chip microprocessor or microcontroller or digital signalprocessor which may be programmed to provide a variety of functions andoperational features. Such programs may be stored in memory 68 for useby the controller 66 in controlling the operation of the object locator42. The paging receiver 60, the paging transmitter 92 and the GPSreceiver 78, while shown as functional blocks, in reality, each may havea number of complex functions incorporated therein. Thus, manyconfigurations and functional operations are possible within the scopeof the block diagram illustrated in FIG. 4. The detailed descriptionwhich follows will illustratively provide descriptions of some of thebasic operational features of the object locator

of the present disclosure. One such feature represented by the signaldetector block 106 will be described hereinbelow in conjunction withFIG. 7.

Referring now to FIG. 5, there is illustrated a flowchart for theoperation of the object locator 42 shown in FIG. 4 in the case where theuser desires to determine the location of the object locator 42. Thiscircumstance may represent any number of user activities including anowner's efforts to determine the location of a pet dog or a pet cat, forexample. Similarly, the operation illustrated in FIG. 5 may also includea situation where an owner desires to track versus time, an object towhich the object locator 42 is attached. Further, the flowchart of FIG.5 may also illustrate the situation when the object locator 42 isattached to a person and it is desired to know the location of thatperson at some particular time or some other previous time as furtherdescribed below. The flow begins at block 202 with the start of thesequence of operations, which is followed by decision block 204 in whichthe object locator 42 seeks to determine whether a page requestinglocation information has been received by the input of the two-waypaging receiver 60. If the result of this determination is in thenegative, then the flow returns to the input of the decision block for aretry. If, however, the result of the query was affirmative, then theflow proceeds to block 206 in which the GPS receiver 78 is enabled toacquire the location coordinates of the object locator 42 by receivingsignals from the global positioning satellite system 50 illustrated inFIG. 1.

Upon successfully acquiring the coordinates of the object locator 42 andthus of the individual object or animal to which the object locator 42is attached, the object locator 42 then operates to store the coordinateinformation in block 208 by loading the coordinate information into thememory 68 of the controller 66 in the object locator 42. Such coordinateinformation may be associated with a time stamp. Such time stamp,derived from the GPS satellite system, may then be stored in block 208for later retrieval. Additionally, such coordinate information mayfurther be associated with other data such as object locator 42operational status or battery condition. The flow then proceeds fromblock 208, where the coordinates were stored in the memory 68, to block210, wherein the object locator 42 is configured to transmit thecoordinates in response to the request received over the two-way pagingsystem 12. The transmission of coordinates will occur in the oppositedirection utilizing the same two-way paging system 12 over which therequest for location coordinates was received in block 204. Followingthe transmission of the coordinates in block 210, the flow proceeds to atimer block 212 which provides a measured interval of time during whichthe object locator 42 attempts to acquire the coordinates at theparticular time from the GPS system 50. It is well known that a typicalGPS system often takes a substantial amount of time to acquire locationcoordinate information from a sufficient number of satellites in orderto fix the location of the object locator 42 with a sufficient degree ofprecision. The time required involves receiving several signals underconditions which may vary widely from instant to instant, which impairsthe ability of the GPS receiver 78 as shown in FIG. 4 to obtain completelocation data to respond to the request received by the paging receiver60 in the object locator 42. The time value represented by the timeroperating in block 212 may be on the order of five to ten minutes, forexample. In block 212, if the timer has not reached the time-out value,then the flow returns to the input of block 206 where the object locator42 again attempts to acquire the coordinates from the GPS system 50.Returning to block 212, if the timer has reached its end value, then theflow proceeds from block 212 to block 214 where the routine ends. FIG. 5thus illustrates a basic mode of operation of the object locator 42. Itwill be appreciated that many variations on this basic operating modeare possible and may be used to enhance the operation of the objectlocator 42. Such features may be programmed into the controller 66 ofthe object locator 42.

Referring now to FIG. 6, there is illustrated a flowchart for theoperation of the object locator 42 in the circumstance where it isactivated to obtain location information from the GPS receiver 78 only,in this illustrative example, when the object locator 42 is in aposition beyond a distance limit relative to the base station or someother defined location from which the request for location coordinateswas initiated. The flowchart in FIG. 6 also shows additional steps inthe operational sequence which may be used to enable and disable the GPSreceiver 78 within the object locator 42. As was pointed out previously,the GPS receiver 78 is typically a device which requires substantialelectrical power to operate and so it is to the advantage of the objectlocator system 10 of the present disclosure to attempt to minimize thepower drawn from the object locator battery 70 in FIG. 4. This may beaccomplished by limiting the operating cycle of the GPS receiver 78 tobecome operational only long enough to obtain the coordinate informationthat is required by the object locator 42.

The flow begins in FIG. 6 with a start block 220 from which the flowproceeds to a block 222, wherein the object locator 42 determineswhether the object locator 42 is beyond a predetermined limit such as aminimum distance from the base station or other defined location makingthe request for location information. If the determination is in thenegative, that is, the object locator 42 is not beyond the predeterminedlimit, then the flow returns to the input of the decision block 222 foranother attempt. This looping will continue as long as the objectlocator 42 is within the predetermined limit established by circuitrywithin the object locator 42 and other portions of the object locatorsystem 10 of the present disclosure. The functional operation of anillustrative example of such a predetermined limit feature will bedescribed further hereinbelow in conjunction with FIG. 7.

Returning now to the flowchart of FIG. 6, the flow proceeds from startblock 220 to a decision block 222 to determine whether the objectlocator 42 has received a query from the base station 18. If a query hasnot been received, the flow proceeds along the “N” path to a timer block224 wherein the object locator 42 may operate a timed sequence toperiodically enable the GPS receiver 78 to acquire location coordinateswhether or not a query is received from the base station 18. When thetimer of block 224 times out, the flow proceeds along the “Y” path to ablock 226 to enable the GPS receiver 78. Returning to decision block,222, if the object locator 42 did receive a query from the base station18, the flow proceeds along the “Y” path to block 226 to enable the GPSreceiver 78.

Continuing with FIG. 6, the flow in the object locator 42 proceeds fromblock 226 to block 228 to acquire the coordinates of the location of theobject locator 42. Thereafter, the flow proceeds to decision block 229to determine whether the object locator 42 is beyond a predeterminedlimit with respect to the base station 18. If the result of thedetermination in block 229 is negative, the flow proceeds along the “N”path to decision block 231 wherein a counter provides for apredetermined number of trials to establish whether the object locator42 is beyond the predetermined limit required in block 229. When thecounter in block 231 completes the last count, the flow proceeds alongthe “Y” path to the input of the decision block 222. Returning now todecision block 229, if it is determined that the object locator 42 isbeyond the predetermined limit, the flow proceeds along the “Y” path toblock 230 to store the location coordinates acquired from the GPSsatellite during the step performed in block 228, wherein the enablesignal applied to the enable terminal 90 thus operates to awaken the GPSreceiver 78 so that it may communicate with the GPS system and obtainlocation information coordinates for the object locator 42. Thus, theflow proceeds from block 226 where the GPS receiver 78 is enabled to ablock 228 where the object locator 42 acquires the coordinateinformation from the global positioning satellite system 50.

Continuing with FIG. 6, upon acquiring the coordinates of the objectlocator 42 from the GPS receiver 78, the controller 66 within the objectlocator 42 causes the location information to be stored in the memory 68of the object locator 42 in the operational block 230 of FIG. 6. Theflow then proceeds to a block 232 where the controller 66 operates todisable the GPS receiver 78 such that it will no longer continue todrain power from the battery, until the next time that it is desired toacquire coordinate information from the GPS system 50. Following thedisabling of the GPS receiver 78 block 232, the flow proceeds to a block234 wherein the object locator 42 provides the location data on outputterminal 98 along path 96 to the data input 94 of the paging transmitter92. The location information is then transmitted via the two-way pagingsystem 12 to the base station shown in FIG. 1. The flow proceeds fromblock 234 following the transmission of the coordinate information to atime-out block 236 where a timer provides an interval of time in whichthe object locator 42 is permitted to acquire the coordinate informationfrom the GPS system, thus maximizing the opportunity to acquire thecoordinates before the object locator 42 becomes inactive. Here thetime-out value may again typically be on the order of five to tenminutes, although the time duration may legitimately be any value thatcorresponds with the particular circumstances of use and, in fact, maybe adjustable in some applications. In the event that the time-out valuehas not been reached in block 236, the operation loops back around tothe input of the time-out block 236 and enables the object locator 42 tocontinue attempting to acquire the location information from the GPSsystem. In the event that the time-out value has been reached, then theflow proceeds along the “Y” path from block 236 back to the start of thesequence at the input to the decision block 222 where the object locator42 is enabled to check whether the object locator 42 is positionedbeyond the predetermined limit as previously explained.

Referring now to FIG. 7, there is illustrated a pictorial block diagramof one configuration that is possible to provide the predetermined limitsignal to the object locator 42. Shown in FIG. 7 is a base station 18coupled with its antenna 126 through a cable 128 and operating toproduce a signal which is radiated according to the radiation patterncharacteristic of the antenna 126 of the base station. Also shown inFIG. 7 is an object locator 42 which includes a signal detector block120 coupled to an antenna 122 through a cable 124. It will be noted thatthe base station 18 is operating in a transmit mode and the objectlocator 42 is operating in a receive mode via antenna 122. The objectlocator 42, by comparing the received signal strength of the signaltransmitted by the base station from antenna 126 with a reference signalstored within the signal detector 120, is able to make a determinationas to where it is in relation to the base station in terms of thedistance that separates the object locator 42 and the base station 18.It is presumed in this example that the signal strength measured betweenthe base station 18 and the object locator 42 falls off in a predictablemanner as compared with the distance that separates the object locator42 from the base station 18. An alternative to comparing the limitsignal with a reference value is to simply utilize the signal-to-noisecharacteristics of the receiver in the object locator 42. When it is nolonger possible to acquire or capture the signal from the base station18, a limit is thereby provided. The limit may be adjusted simply byadjusting the base station signal strength. By way of illustration, apredetermined limit may thus be established by controlling the signalstrength of the base station 18 signal such that at an imaginaryboundary 130 surrounding base station 18 is defined. The signal strengthis of a sufficiently low value which can just be detected by the signaldetector 120 in the object locator 42 at the imaginary boundary 130.Thus, if the object locator 42 antenna 122 is greater than a distanceindicated by the radius “r” from the base station 18, then no signalwill be detected (or it will be below an acceptable threshold) and theobject locator 42 is presumed to be beyond the predetermined limitrepresented by the distance “r”, which may be thought of as anacceptance radius. If, however, the object locator 42 receives ordetects the signal emitted by the base station 18 (or it is above thepredetermined threshold), then it is presumed that the antenna 122 ofthe object locator 42 is within the radius “r” and the object locator 42must not be, at that point, activated to attempt to acquire locationinformation from the GPS system 50.

Referring now to FIG. 8, there is illustrated a block diagram includingfeatures which may be implemented in the base station 18 to process thelocation information received from the object locator 42. In the oneembodiment shown in FIG. 8, the base 302 includes a paging receiver 304which has a receiving antenna 306 coupled to the paging receiver 304 bya cable 308. The output of paging receiver 304 is supplied at an output310 along path 312 to an input 314 of a processor 316 which receives andprocesses the location information for output or display. In theillustrative example of FIG. 8, the information is stored along a path318 in a register 320 from which the information can be retrieved alongpath 322 by the processor 316 for output at terminal 324 along path 326to the input 328 of a data display 330. In this simple exampleillustrated by the block diagram of FIG. 8, the location information isprocessed for display as data which may be in the form of degrees oflongitude and latitude, the names of the closest major streetintersections or in terms of polar coordinates such as an azimuthheading and a distance between the base station 302 and the objectlocator 42.

Referring now to FIG. 9, there is illustrated an alternate embodimentshowing a base station 350 which includes a paging receiver 304. Pagingreceiver 304 receives location information transmitted by object locator42 to the antenna 306 of the paging receiver 304 along cable 308. Pagingreceiver 304 is coupled from an output 352 along path 354 to an input356 of processor 358 in the base station 350. Processor 358 may alsohave access to a register 380 along path 378 from which the processor358 may further obtain stored location information along path 382 fromregister 380. Such location information is, of course, available fromthe GPS receiver 368 which is coupled at an output 370 along path 372 toan input 374 to processor 358. This GPS receiver 368 is part of basestation 350 and enables the base station 350 to provide an enhanceddisplay of the location information obtained from the object locator 42.

Continuing with FIG. 9, there is shown a GPS display 366 that obtainsdata concerning the location coordinates from processor 358 at an output360 which flows along path 362 to an input to the GPS display 366 atinput 364. The GPS display 366 is configured to provide a map of thearea that includes both the base station 350 and the object locator 42,and thus display the relative position of each component of the objectlocator system 10 with respect to the other. As is typical with GPSdisplay units, a map may be shown with streets or thoroughfaresindicated thereon and indicia included in the display showing therespective location of the base station 350 and of the object locator42.

Referring now to FIG. 10, there is shown a flowchart of the operation ofthe combined units of the object locator system 10 of the presentdisclosure as illustrated in FIG. 1. The flow begins at block 402 wherethe routine starts and thereupon flows to block 404 in which the basestation 18 requests location information by paging the object locator42. In this block 404, the base station 18 transmits a request forlocation information to the object locator 42. The flow proceeds fromblock 404 to block 412 where the object locator 42 proceeds through thesequence to enable the GPS receiver 78 in order to obtain new locationcoordinate information. Thereupon the flow proceeds to a block 406wherein the object locator 42 checks its own memory—see, for example,the block diagram of the object locator 42 shown in FIG. 4—whereupon theflow proceeds to block 408 where the object locator 42 determineswhether, in fact, there are coordinates in its memory. If the result isin the affirmative, then the flow proceeds along the “Y” path to a block410 where a determination is made by the object locator 42 whether thecoordinates stored in its memory are current. If the result in block 410is affirmative, then the flow proceeds along the “Y” path to a block 420where the object locator 42 will fetch the coordinate information fromits memory 68 shown in FIG. 4 and set up the object locator 42 totransmit the coordinates to the base station in a block 422. Thereuponthe flow proceeds to a block 424 wherein the base station 18 makes adetermination as to whether it has received the requested coordinateinformation from the object locator 42. If the result is affirmative,then the flow proceeds along the “Y” path to a block 428 where the basestation 18 proceeds to output or display the coordinate information tothe user at the base station 18. Thereupon, the flow proceeds from block428 to a block 430 wherein the routine ends.

Returning to block 424 of FIG. 10, if the base station 18 determinesthat it did not receive the coordinate information as requested, thenthe flow proceeds to block 426 along the “N” path to a decision block426. In block 426, the base station 18 determines whether the mostrecent page of the object locator 42 was, in fact, the last attemptpermitted within the protocol for the base station operation. If theresult is affirmative, then the flow proceeds along the “Y” path toblock 418 where the object locator 42 operates to disable the GPSreceiver 78 so that it no longer uses power from the battery 70 of theobject locator 42 and thereafter proceeds to block 430 where the routineends. If, however, the result of the determination in block 426 wasnegative, then the flow returns to the start of the routine at the inputto block 404 where the base station 18 re-attempts to page the objectlocator 42.

Returning now to block 408 in FIG. 10, the object locator 42 checks todetermine whether location coordinate information is, in fact, in thememory 68 of the object locator 42. If the result is negative, the flowproceeds along the “N” path to block 414 where the object locator 42acquires the new coordinate information and, as previously described,proceeds in block 416 to store the new coordinate information in memory68 of the object locator 42. The flow then returns to the input of block412 wherein the GPS receiver 78 is enabled.

The above noted object location system was disclosed as being utilizedin conjunction with a pet, such that the pet owner can determine thelocation of their wayward pet. The locator, as described hereinabove, inone embodiment, is triggered to determine the location of the pet inresponse to receiving a signal from a paging system. The paging systemutilizes existing infrastructure in order to direct a message over awireless link to a moving object, such as the pet. This only requiresthe inclusion of a paging receiver tuned to the frequency of the pagingtransmitters. Of course, there are multiple paging transmitters disposedabout any given area. If the pet wandered outside of the range of all ofthese paging transmitters, then the system will not work. This wouldthen, in the alternative, require a direct RF link to the pet.

Once the object locator 42 has received the request, the locator 42 willdo one of two things. First, it could merely search its own memory todetermine if location coordinates are stored therein from a previousacquisition operation of the GPS system. If so, these could betransmitted back to the requester. Alternatively the GPS system isturned on in response to receiving the request and then the locationdetermined. Of course, as described hereinabove, there are provisionsmade for situations wherein the GPS system cannot be acquired.

When the information is to be transmitted back to the user, thedisclosed embodiment sets forth the use of a two-way pager. Thesetwo-way pagers are desirable in that they make use of the existinginfrastructure of the paging system. This is facilitated by theinclusion of a plurality of receivers at each of the paging towers orpaging “sticks ” which allow the signal to be received and forwardedback to a central station. This central station then processes theinformation received and forwards it to the user. This information, asdescribed hereinabove, is in the form of coordinates. This coordinateinformation can then be relayed back to the user in any number of ways.It could actually be forwarded via a paging channel to the user, whichmight result in a latency of approximately two to five minutes.Alternatively, it could be transmitted directly to the user, providingthere was such an infrastructure. This infrastructure could evenincorporate the use of a cellular telephone system. In any event, it isnecessary to have the coordinates relayed back to the user in order todetermine the relative location of the user and the wayward pet. Thetwo-way system that can be utilized is a conventional system, oneexample of such a conventional system described in U.S. Pat. No.5,708,971, issued Jan. 13, 1998, entitled “TWO-WAY PAGING SYSTEM ANDAPPARATUS,” which is incorporated herein by reference.

Although the preferred embodiment has been described in detail, itshould be understood that various changes, substitutions and alterationscan be made therein without departing from the spirit and scope of theinvention as defined by the appended claims.

What is claimed is:
 1. A portable locator, comprising: a first devicefor receiving and transmitting paging signals via a two-way pagingsystem during communication with a base station wherein said firstdevice has transmission/reception characteristics that can be affectedby its physical proximity to other objects; a second device forreceiving location information signals from a satellite of a globalpositioning system wherein said second device has transmission/receptioncharacteristics that can be affected by its physical proximity to otherobjects; a third device, coupled to said first and second devices andfor processing said location information signals upon activation, toprovide location information for communication in said transmitting ofpaging signals; and a portable housing, for supporting said first,second and third devices and for securing said housing to a person anddisposable on said person is such a manner as to facilitateelectromagnetic interaction with said signals such that the proximity ofsaid first and second devices to the person is such that thetransmission/reception characteristics thereby are affected minimally;wherein said locator may be activated to provide said locationinformation by reception of a query via a receiving paging signal or bytraversing a predetermined distance limit or by a timer.